1. Field of the Invention
The present invention relates generally to fuel injection for engines of automotive vehicles, and more particularly to electronic control of the firing of fuel injectors on an engine for an automotive vehicle.
2. Description of Related Art
Typically, an engine of an automotive vehicle has one or more fuel injectors for delivering fuel from a fuel source to cylinders of an internal combustion engine. Generally, a sensor on a distributor of the engine transmits a signal from the distributor as to the crank angle of the engine. This distributor reference signal is received by an electronic control unit (ECU) which outputs a signal to fire the fuel injectors at predetermined states of the distributor reference signal.
Currently, multi-port fuel injection systems consist of either "grouped" or "banked" fuel injector firings (e.g., injectors fired in pairs, two at a time) or "sequential" fuel injector firings (e.g., injectors fired sequentially one at a time) Both of these systems typically utilize the distributor reference signal to synchronize the firing of the fuel injectors with the engine s valve events. The time when a cylinder's fuel injector is fired relative to that cylinder's valve event is constant for every firing of that fuel injector.
In normal sequential fuel injector timing, each cylinder is fired in a sequential order. However, a need exists to vary the time when a fuel injector is fired to fuel a cylinder, relative to that cylinder's valve events. For example, during engine idle conditions, it may be desired to inject fuel into the cylinder when an intake valve is open, while during engine acceleration conditions, it may be desired to inject fuel well before the intake valve opens to obtain the best fuel preparation Also, a need exists to inject fuel when an engine transient occurs after an initial fuel injector pulse is delivered to avoid a lean or rich engine operating condition.